1. Field of the Invention
This invention is directed to method and apparatus for the depuration of shellfish, and more particularly to such depuration of oysters using a novel tank configuration, closed cycle water flow and purification system in conjunction with the bacteriological testing of the shellfish and the water to determine the level of total coliform, fecal coliform, Vibrio Vulnificus and Vibrio parahaemolyticus for monitoring the purification process.
2. Related Art
The depuration of shellfish, and particularly oysters, has been attempted for some time, but historically such depuration attempts have not been commercially successful, especially on a large commercial scale, primarily because of the lack of engineering in the design of the depuration system coupled with the lack of integration with the biological requirements of the oysters to induce self-purging.
The major problems encountered with both small and large depuration units have been the presence of dead spots in the water column in the tank, the inadequate sterilization of the sea water, and the failure to provide an environment conducive to the self-purging of the oysters. Additionally, the costs of depurating oysters on a small scale have caused investors to hesitate from investing in new projects that would meet the demands of producers, brokers and retailers.
U.S. Pat. No. 4,537,149 entitled "Method and Apparatus for Cleaning Tainted Shellfish", disclosed a depuration tank having a bottom grid of pipes for cleaning the tank.
U.S. Pat. No. 3,641,982 entitled "Bivalvia Depuration System", provides tank input pipes for spraying water across the top of the tank and at two levels beneath the top of the water to keep water moving rapidly in the tank.
U.S. Pat. No. 3,888,210 entitled "Fish Husbandry System Utilizing at Least Partial Recirculation of Water", discloses a fish rearing tank having an overflow trough.
U.S. Pat. No. 3,870,019 entitled "Oyster Culture Basket", discloses the flow of water outwardly through holes in standpipes.
U.S. Pat. No. 3,418,138 entitled "Apparatus for and Methods of Treating Bivalves", provides circulation of water in the tank via a conduit at one end of the tank and uses a pipe with holes for dripping water into the other end of the tank and rotary pumps for circulating the water.
U.S. Pat. No. 4,653,429 entitled "Process and Apparatus for Preparation of Bivalves for Human Consumption", shows water injected into a tank via peripherally located injection nozzles and is drained by drains at the bottom of the tank.